Biocompatible osteogenic band for repair of spinal disorders

ABSTRACT

Methods of repairing a joint formed by at least two bone sections are provided wherein a biocompatible osteogenic band fabricated from an osteogenic biological material such as bone, tendon, ligament and collagen is affixed to two or more bone sections.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to methods for repairing spinaldisorders. More particularly, the present invention relates to a methodof repairing spinal disorders, especially those requiring spinal fusion,using a biocompatible osteogenic band which induces new bone growthformation at the site of implantation.

[0003] 2. Description of the Related Art

[0004] The vertebral column (spine) is a biomechanical structurecomposed of a series of joints known as motion segment units. Eachmotion segment unit includes two adjacent vertebrae and their facetcapsules, the intervertebral disc, and connecting ligament tissue. Thespine is divided into four major regions which include the cervical,thoracic, lumbar and sacral regions and functions to protect the spinalcord and nerve roots, and provide support to the body. Theintervertebral disc is located between the two endplates of adjacentvertebrae and is composed of the nucleus pulposus (a gel-like balllocated at the center of the disc) and annulus fibrous (collagen fiberssurrounding the nucleus pulposus). The intervertebral disc stabilizesthe spine, and provides the spine with resiliency and the ability towithstand compression, rotation and bending strain. The facet capsulesare bony elements which aid in the support of compressive loads andresist torsional motion. Ligaments connected to the spine support loadsin tension and help provide spinal stability by limiting excessive rangeof motion and absorbing energy applied due to trauma.

[0005] Various types of spinal disorders are known and include kyphosis(backward curvature of the spine), spondylolysis, spondylolisthesis(forward displacement of a lumbar vertebrae), scoliosis (abnormalcurvature of the spine) and disorders involving ruptured, slipped,damaged and diseased discs, damaged vertebrae, and the like. Patientssuffering from the aforementioned disorders typically experience severepain, numbness, decreased mobility, muscle weakness and nerve damage.

[0006] Spinal fusion is frequently used as a treatment for suchdisorders and is achieved by formation of a bony bridge between adjacentmotion segments eliminating the intervertebral joint. Spinal fusion canbe accomplished within the disc space, anteriorly between adjacentvertebral bodies and/or posteriorly between consecutive processes, e.g.,transverse processes, laminae or other posterior elements of thevertebrae.

[0007] One frequently used spinal fusion technique involves removal ofthe intervertebral disc and insertion of an anterior supportingstructure, e.g., bone grafts, bone substitutes, plugs, bone dowels,cages, and the like, into the intervertebral disc space to preventcollapse of the disc space and promote fusion of the adjacent vertebrae.To ensure proper growth and fusion between the affected adjacentvertebrae, the posterior side of the spine is frequently stabilized byutilizing a rigid metallic implant, e.g., a plate, rod, wire or strip,which spans the adjacent vertebrae to re-create a load distributionsimilar to that of the intact spine. These metallic implants arecommonly referred to throughout the relevant scientific and medicalliterature as “tension bands.”

[0008] The use of such metallic implants to stabilize the spine andfacilitate fusion presents several disadvantages. One disadvantageencountered utilizing such metallic implants is that once fusion occursthe metallic implant becomes superfluous and remains as a permanentforeign fixture. As the metallic implant loosens enough to allowrelative motion, particulates are generated as wear debris. This weardebris then has the potential to cause a foreign body response. Metallicimplants are also subject to fatigue failure due to repeated cyclicloading. An implant that is remodeled, and then repaired as it laterbecomes damaged, will not fail due to fatigue. Another disadvantage isthat the implanted metallic implant itself possesses ferromagneticproperties and thus prevents the use of post-operative plain filmX-rays, MRI or CT scan imaging due to scattering of the image. Yetanother disadvantage is that when such metallic implants are placed overbone tissue, any tension load placed on the spine is transmitted to theimplant rather than the bone tissue, thereby “stress shielding” thebone. Over a period of time, bone tissue that is shielded from tensionloads is removed by the body thereby weakening the structure of thebone. Accordingly, removal of the implant by a second operation may berequired to prevent loss of bone tissue caused by stress shielding.

[0009] In view of the aforementioned limitations posed by using rigidmetallic implants to stabilize the spine and facilitate fusion, there isa need to provide a method of treating spinal disorders that willprovide for the fusion of bone at the implant site, thereby providing agraft that will not fail mechanically or cause rejection in the patient,and will not require removal in a subsequent operation.

[0010] Therefore, it is an object of the present invention to provide amethod of stabilizing the spine which overcomes the limitations of rigidmetallic implants.

[0011] It is a further object of the present invention to provide amethod of stabilizing the spine with a device that is non-antigenic andwill not be rejected by the host.

[0012] It is a further object of the present invention to provide amethod of stabilizing the spine with a device that is biocompatible andwill not require removal in a subsequent operation.

[0013] It is a further object of the present invention to provide amethod of stabilizing the spine with a device that is osteogenic andthat adequately supports tension loads.

[0014] It is a further object of the present invention to provide amethod of stabilizing the spine with a device that will avoid stressshielding.

[0015] It is a further object of the present invention to provide amethod of stabilizing the spine with a device that supports fusionbetween adjacent vertebrae.

[0016] It is a further object of the present invention to provide amethod of stabilizing the spine with a device which can be utilized inconjunction with an anterior supporting structure.

[0017] Other objects of the invention will be apparent to those skilledin the art in view of the above objects and the foregoing specification.

SUMMARY OF THE INVENTION

[0018] These and further objects of the invention are obtained by amethod for repairing a spinal disorder which comprises affixing abiocompatible osteogenic band to two or more vertebrae of a spine tomaintain the two or more vertebrae under tension, wherein the band isfabricated in whole or in part from biocompatible fibers of a native,biosynthetic, or synthetic polymeric, connective tissue or plantconnective tissue-like containing component that is osteoinductive orhas been treated to be osteoinductive. The osteogenic material caninclude bone, tendon, ligament, silk, collagen, elastin, reticulin,cellulose, alginic acid, chitosan, small intestine submucosa,biocompatible polymers or combination thereof which has been renderedosteogenic by one or more procedures described hereinbelow. A suitablematerial is disclosed in the U.S. Provisional Application filed on evendate herewith under Certificate of Express Mail # EL713572920US, thecontents of which are incorporated by reference herein.

[0019] A method for repairing a spinal disorder is also provided whichcomprises inserting an anterior supporting structure into a disc spacebetween adjacent vertebrae of a spine and affixing a biocompatibleosteogenic band to two or more vertebrae of the spine to maintain thetwo or more vertebrae under tension.

[0020] Affixation of the foregoing biocompatible osteogenic band to thespine leads to new bone ingrowth by one or more biological mechanismssuch as osteogenesis, osteoconduction and/or osteoinduction or by one ormore physical mechanisms such as providing a support for new bonegrowth. The expression “osteogenic material” as utilized herein shalltherefore be understood as referring to a material which willparticipate in the process of new bone growth regardless of themechanism(s) involved. The osteogenic material can be obtained fromsources which are not in themselves osteogenic but are renderedosteogenic by incorporation and/or associating therewith one or moreosteogenic components. Accordingly, unlike metallic implants, thebiocompatible osteogenic band of this invention contributes to thedevelopment of a fusion preferably across vertebral bodies of theposterior spine and aids in the repair and stabilization of the spine.

[0021] Another advantage of the present invention is that thebiocompatible osteogenic band preferably provides posterior tensileloading, thereby recreating a load distribution similar to that of theintact spine.

[0022] Another advantage of the present invention is that, unlikeconventional metallic implants, the biocompatible osteogenic band issufficiently flexible to allow affixation to a vertebral site yetsufficiently strong, tough and inextensile to withstand appliedexcessive force. Because the material is osteogenic, new bone is formedaround and within the implant and the biocompatible osteogenic band isincorporated with new bone tissue via the process of remodeling.Accordingly, unlike a metallic implant which persists long after itsuseful life, it is not necessary to remove the biocompatible osteogenicband in a subsequent operation.

[0023] Another advantage of the present invention is that, unlikeconventional metallic implants, the biocompatible osteogenic band willnot stress shield the bone. In addition, unlike metallic implants, thebiocompatible osteogenic band does not interfere with the use ofpost-operative plain film X-rays, or MRI and CT scans.

[0024] Other advantages of the present invention will become apparent toone skilled in the art from the following written description andaccompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIGS. 1A-1C are diagrammatic representations of tension bandsfabricated from elongated sections of bone. In FIG. 1A the elongatedsection of bone is cut or machined to provide end and middle portionspossessing the same width. In FIGS. 1B-1C the elongated section of boneis cut or machined to provide end portions possessing a greater widththan the middle portion, and end portions possessing round (FIG. 1B) andsquare (FIG. 1C) configurations that taper off. FIG. 1A alsoschematically depicts an elongated section of bone cut or machined toexhibit threads on one end and an attachment hole at the other end.FIGS. 1B-1C also schematically depict an elongated section of bone cutor machined to exhibit an attachment hole on each end.

[0026]FIG. 2 is a diagrammatic representation of a segmentallydemineralized bone section wherein the end portions are fullymineralized (solid lines) and the middle portion is partiallydemineralized (dots).

[0027] FIGS. 3A-E are diagrammatic representations of demineralized bonestrips arranged into various structures.

[0028]FIG. 4 is a diagrammatic left lateral view of the tension banddescribed herein affixed to vertebrae of the lumbar region of theposterior spine.

[0029]FIG. 5 is a diagrammatic posterior view of two tension bandssymmetrically attached to each side of the lumbar region of theposterior spine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The present invention is directed to a novel method of repairinga spinal disorder which involves affixing a biocompatible osteogenicband to two or more vertebrae of the spine, preferably the posterioraspect of the spine, to maintain the two or more vertebrae undertension. The foregoing biocompatible osteogenic band can be used aloneor in conjunction with other classical approaches to repair a spinaldisorder, such as the use of an anterior supporting structure asdescribed in more detail below. Spinal disorders which can be repairedby the method described herein include, but are not limited to, rupturedand damaged discs, degenerative disc disease, spondylolysis,spondylolisthesis, scoliosis, spinal injuries caused by trauma orsurgery, etc.

[0031] The biocompatible osteogenic band is fabricated in whole or inpart from various materials, particularly connective type biologicalmaterial obtained from human and animal tissues, plants, and insectswhich include, but are not limited to, e.g., bone, tendon, ligament,silk, collagen, elastin, reticulin, cellulose, alginic acid, chitosan,small intestine submucosa or combinations thereof. The biologicalmaterial can be autogenic, allogenic or xenogenic in origin. Thebiological material can also be obtained from microorganisms,particularly genetically engineered microrganisms such as yeast andbacteria and genetically engineered eucaryotic cell cultures such aschinese hamster ovary cell lines, HeLa cells, etc. For example, U.S.Pat. Nos. 5,243,038 and 5,989,894, each incorporated herein byreference, describes the expression of spider silk protein, collagenproteins, keratins, etc., using genetically engineered microrganisms andeucaryotic cell lines.

[0032] The biocompatible osteogenic band can also be fabricated in wholeor in part from synthetic biocompatible polymers that have been renderedosteogenic as described below. Suitable biocompatible polymers wouldinclude, for example, poly(lactide), polyglycolides, poly(epsilon-caprolactone), etc.

[0033] To function effectively in repairing the spine, the biocompatibleosteogenic band, particularly when fabricated in whole or in part frombiological material such as bone, tendon, ligament, and small intestinesubmucosa tissue, is first processed to clean the tissue of blood anddebris, and to sterilize the tissue by routine procedures as describedbelow. The processed tissue is then fashioned into one or more elongatedsections. The dimensions of an elongated section are selected so thatthe material possesses sufficient length to span and be affixed to theaffected vertebrae, and also possesses sufficient width and thickness toimpart toughness, flexibility and strength to the section. One skilledin the art will recognize that the elongated section of material,particularly an elongated section of bone, can be further cut ormachined by any convenient method into a variety of different shapes asshown in FIGS. 1A-1C. For example, FIG. 1A schematically depicts oneembodiment of an elongated section of bone which is further cut ormachined to provide end and middle portions possessing the same width.FIGS. 1B-1C schematically depict other embodiments wherein an elongatedsection of bone is further cut or machined to provide end portionspossessing a greater width than the middle portion, and end portionshaving a round (FIG. 1B) or square (FIG. 1C) configuration that tapersoff. Likewise, the processed tissue, when fibrous or prepared as thinsections, can be woven or knitted to form a cloth-like material usefulas the biocompatible osteogenic band herein. Another configuration of abiocompatible osteogenic band useful in the practice of the inventionherein would be a composite structure such as a central core ofdemineralized monolithic bone surrounded by a weave of bioabsorbablefibers. The anchoring of the implant would be assisted by thebioabsorbable fibers while the demineralized monolithic bone core wouldprovide osteogenic characteristics. The term “monolithic” as utilizedherein refers to a unitary portion of bone having a total surface areaof at least 40 mm³.

[0034] It is further recognized that the end portions of an elongatedsection can be cut or machined to include threads, grooves, driver head,fasteners, rivets, screws, bolts, pins, etc., to aid in affixing eachend portion of the elongated section to the vertebrae. FIG. 1Aschematically depicts one embodiment of an elongated section of bonewhich is machined to exhibit threads 1 at one end and an attachment hole2 at the other end. FIGS. 1B-1C schematically depict other embodimentsof an elongated section of bone which is machined at both ends toexhibit an attachment hole 2.

[0035] Accordingly, the overall dimensions of the elongated sections ofthe biocompatible osteogenic band can vary widely depending on thedistance between affected vertebrae, the site, and the method ofaffixation. Typically, the dimensions of the biocompatible osteogenicband will range from about 1 cm to about 1 meter in length, preferablyfrom about 3 cm to about 8 cm in length, from about 2 mm to about 30 mmin thickness, preferably from about 2 mm to about 10 mm in thickness,and from about 2 mm to about 30 mm in width, preferably from about 2 mmto about 10 mm in width.

[0036] While fully mineralized bone, tendon, ligament, silk, collagen,elastin, reticulin, cellulose, alginic acid, chitosan, small intestinesubmucosa and biocompatible polymers in themselves are not osteogenic,such materials can be rendered osteogenic by subjecting the material tovarious procedures and/or incorporating in, or associating with, thematerial various osteogenic components. For example, the mineral contentof bone tissue can be reduced by demineralization, a process whichresults in the removal of the inorganic components of the bone, largelyhydroxyapatite, which gives bone its characteristic rigidity andstructural properties. The resultant demineralized bone is flexible andosteogenic. Bone, tendon, ligament, silk, collagen, elastin, reticulin,cellulose, alginic acid, chitosan, small intestine submucosa andbiocompatible polymers can be rendered osteogenic by association with,or incorporation of, various osteogenic components which include, butare not limited to, growth factors such as bone-derived growth factor,bone morphogenic proteins, osteogenic proteins such as OP-1, hormones,growth hormone, platelet derived growth factor (PDGF), insulin-likegrowth factors (IGF-1)(IGF-2), DNA encoding various therapeutic agentssuch as growth factors and hormones, gene activated matrix, i.e., amatrix containing DNA encoding therapeutic proteins utilized to promotecell growth, which in turn, promote DNA transfer into repair cells,demineralized bone in the form of particles, powder, gel, liquid, etc.,ceramic powders of calcium phosphate and/or apatite (hydroxyapatite) andbioglasses. Bone morphogenic proteins can be obtained from, e.g.,Genetics Institute, Inc. (Cambridge, Mass.) and Stryker Corporation(Kalamazoo, Mich.), and may also be prepared by one skilled in the artas described, e.g., in U.S. Pat. Nos., 5,187,076, 5,366,875, 4,877,864,5,108,922, 5,116,738, 5,013,649, 5,106,748, WO93/00432, WO94/26893 andWO94/26892, each incorporated herein by reference.

[0037] All osteogenic components are contemplated whether they areobtained as above or isolated from bone. Methods for isolating bonemorphogenic protein from bone are described, e.g., in U.S. Pat. No.4,294,753, incorporated herein by reference. Methods of preparingdemineralized bone powder, demineralized bone particles, anddemineralized bone in the form of a liquid, and demineralized bone inthe form of a gel are well known in the art as described, e.g., in U.S.Pat. Nos. 5,314,476, 5,507,813, 5,073,373, and 5,405,390, respectively,each incorporated herein by reference. Methods of preparing osteogenicproteins, such as OP-1 are described, e.g., in U.S. Pat. No. 6,048,964,incorporated herein by reference. Methods of transferring DNA encodingtherapeutic proteins into repair cells utilizing gene activated matrixare described, e.g., in U.S. Pat. No. 5,962,427 incorporated herein byreference. Methods of preparing ceramic powders of calcium phosphateand/or hydroxyapatite are described, e.g., in U.S. Pat. No. 4,202,055and 4,713,076, each incorporated herein by reference. Methods ofpreparing bioglasses are described, e.g., in WO 98/44965, incorporatedherein by reference. Suitable methods of incorporation or association ofsuch osteogenic factors include coating, immersion saturation,dispersing, packing, spraying, e.g., plasma spraying, injecting into thebone tissue, etc.

[0038] When the biocompatible osteogenic band is fabricated from bone,the bone is preferably chosen from a cortical bone, such as from thefemur, tibia, fibula, radius or ulna. The bone can be obtained from anautogeneic, allogeneic or xenogeneic source, and is preferably obtainedfrom an autogeneic or allogeneic source.

[0039] In one embodiment, the biocompatible osteogenic band comprises atleast one elongated section of bone and preferably a plurality ofelongated sections of bone. Typically, the bone is obtained from asuitable vertebrate and processed by conventional techniques to removeblood and lipid from the bone. The bone can then be cut into elongatedsections by techniques which are well known in the art, e.g.,longitudinally cutting an entire bone section or relatively largeportion of bone into elongated sections using a band saw or adiamond-bladed saw, or milling the surface of an entire bone orrelatively large portion of bone. Alternatively, the bone can be cut bymaking transverse cuts to prepare a bone section of the appropriatelength, followed by longitudinal cuts using a band saw or a diamond cutsaw. As stated above, elongated section(s) of bone can be further cut ormachined into a variety of different shapes. In overall appearance theelongated sections of bone can be described as narrow or thick strips,segments, sheets, rods, struts, etc. The elongated bone sections can befurther processed to remove residual blood and lipid residue.

[0040] Prior to or subsequent to cutting or milling of the bone intoelongated sections, the bone section(s) are preferably demineralized toreduce the inorganic content of the bone. The mineral content of bonecan be removed to varying degrees. The term “fully demineralized” as itapplies to an elongated bone section refers to a bone section possessingless than about 8, preferably less than 1, weight percent of itsoriginal inorganic mineral content. The term “partially demineralized”as it applies to an elongated bone section means that the elongated bonesection possesses from about 8 to about 90 weight percent of itsoriginal inorganic mineral content. The term “superficiallydemineralized” as it applies to an elongated bone section refers to abone section possessing at least 90 weight percent of their originalinorganic mineral content. The unmodified term “demineralized” as itapplies to an elongated bone section is intended to cover any one orcombination of the foregoing types of demineralized, elongated bonesections. The use of superficially, partially or fully demineralizedbone is beneficial since it exhibits osteogenic activity unlike fullymineralized bone.

[0041] Demineralization of the elongated bone sections can be conductedusing conventional procedures that are well known in the art, e.g.,subjecting the bone section to strong acids such as hydrochloric acid asdescribed, e.g., in Reddi et al., Proc. Nat. Acad. Sci. 69:1601-5(1972), incorporated herein by reference. The extent of demineralizationis a function of the strength of the acid solution, the shape of thebone and the duration of the demineralization treatment. Reference inthis regard may be made to Lewandrowski et al., J. Biomed. MaterialsRes. 31:365-372 (1996), incorporated herein by reference.

[0042] In a preferred bone demineralization procedure, the elongatedbone section or sections are subjected to a defatting/disinfecting stepwhich is followed by an acid demineralization step. A preferreddefatting/disinfectant solution is an aqueous solution of ethanol, theethanol being a good solvent for lipids and the water being a goodhydrophilic carrier to enable the solution to penetrate more deeply intothe bone. The aqueous ethanol solution also disinfects the bone bykilling vegetative microorganisms and viruses. Ordinarily at least about10 to 40 weight percent by weight of water (i.e., about 60 to about 90weight percent of defatting agent such as alcohol) should be present inthe defatting/disinfecting solution to produce optimal lipid removal anddisinfection within the shortest period of time. The preferredconcentration range of the defatting solution is from about 60 to 85weight percent alcohol and most preferably about 70 weight percentalcohol. Following defatting, the bone is immersed in acid over time toeffect its demineralization. Acids which can be employed in this stepinclude inorganic acids such as hydrochloric acid and organic acids suchas peracetic acid. Generally, the concentration of inorganic acidutilized to achieve demineralization is from about 0.1N to about 2N andmore preferably from about 0.2 N to about 1.0 N. The time of exposure tothe acid is increased for lower acid concentrations and decreased forthe higher acid concentrations. After acid treatment, the elongated bonesection(s) are rinsed with sterile water for injection, buffered with abuffering agent to a final predetermined pH and then finally rinsed withwater for injection to remove residual amounts of acid and bufferingagent or washed with water to remove residual acid and thereby raise thepH.

[0043] In a particularly useful embodiment, the elongated bone sectionor sections are segmentally demineralized. The term “segmentallydemineralized” as applied to the elongated bone section(s) refers toelongated bone section(s) wherein one or both end portions of the bonesection(s) remain fully mineralized or are surface demineralized and themiddle portion of the bone section(s) is fully or partiallydemineralized. The extent of demineralization of the segmentallydemineralized bone section is generally up to about 10 percent for oneor both end portions and at least 50 percent for the middle portion. Thefully or partially demineralized middle portion imparts to the elongatedbone section(s) sufficient flexibility and strength to allow thatportion of the bone section to bear the load of the posterior spine,while each end portion of the elongated bone section(s) is securelyaffixed to the vertebral body at the sites of affixation. FIG. 2schematically depicts a segmentally demineralized bone sectionpossessing fully mineralized end portions 3 and a partiallydemineralized middle portion 4. The segmentally demineralized bonesection can be prepared by procedures known in the art as described,e.g., in WO 99/21515 and U.S. Pat. No. 6,090,998, each incorporatedherein by reference. For example, the end portions of the bonesection(s) can remain fully mineralized by protecting that portion withany type of protective device or composition such as plastic wrap,paraffin, a rubber or latex covering, and the like. The remaining middleportion of the bone section(s) are then demineralized according tomethods known in the art, e.g., use of hydrochloric acid solution asdescribed above. As another example, the segmentally demineralized bonesection can be prepared by placing collar shields around the endportions of the bone section and allowing the acid solution to flow overthe middle portion of the bone section. Preferably, the point of contactof the hydrochloric acid solution with the middle portion of the bonesection(s) is varied over the duration of the demineralization processto produce a gradual transition from a fully mineralized end portion toa fully or partially demineralized middle portion.

[0044] Alternatively, the end portions of the elongated bone section(s)can be surface demineralized by any convenient method. For example,entire bone section(s) can be subjected to demineralization conditionsfor a desired period of time sufficient to demineralize only the surfaceof the elongated bone section(s). The end portions of the bonesection(s) can then be washed and rinsed with sterile water, and coveredwith a protective device as described above. Subsequently, the middleportion of the elongated bone section(s) can be subjected to furtherdemineralization.

[0045] The demineralized, elongated bone section(s) can be usedimmediately by affixing the bone section(s) to the region of the spinein need of repair or it can be stored under aseptic conditions, e.g.,freeze dried, and then rehydrated prior to use. The bone section(s) canbe further cut or sized to conform to the site being repaired.

[0046] If desired, elongated bone section(s) can be treated withchemical agents, such as hydrogen peroxide and with enzymes to modifythe mechanical properties and chemical composition of the bonestructure. In addition, the bone section(s) can be treated with chemicalagents, e.g., glutaraldehyde, to reduce the antigenicity of thesection(s).

[0047] The flexible demineralized bone sections can be arranged to forma variety of different structures as shown in FIGS. 3A-3E. For example,three or more demineralized, elongated bone sections can be woventogether to form a braid (FIG. 3A). A plurality of demineralized,elongated bone sections can be aligned longitudinally and twistedtogether to form a multi-bone section bundle, which can then be used toform a multi-bone section braid of three or more bundles (FIG. 3B). Thedemineralized bone sections can be longitudinally aligned to form asingle untwisted bundle (FIG. 3C) or twisted to form a single-twistedbundle (FIG. 3D). Two or more bundles of multi-bone sections can bewrapped around each other to form a two or more bundle helix (FIG. 3E).The end of the tension band is sealed into a mesh tube 5 made from abioabsorbable or non-bioabsorbable polymer.

[0048] In one embodiment used to prepare a tension band of braidedsections of demineralized bone (FIG. 3B), demineralized bone sections(approximately 6 bone sections) are combined longitudinally into threesmall bundles, each having from about 1 to about 3 bone sections. Thesebundles are first braided at the mid-length and then folded at thebraided region to form a turn and a loop 6. The six bundles are thenrecombined to form three bundles which are then braided.

[0049] Various methods of braiding and types of braids are alsodescribed, e.g., by Shaw, KNOTS—Useful & Ornamental, Bonanza Books, NewYork (1983), incorporated herein by reference. The ends of the braideddemineralized bone section can be glued together using a fixation agentto prevent the braided ends from unraveling or-sealed into a mesh tube 5as described above.

[0050] In another embodiment, demineralized bone strips can be cut fromsheets composed of elongated bone particles, commercially available asGRAFTON® Flex (Osteotech, Eatontown, N.J.) as described, e.g., in U.S.Pat. No. 5,507,813, incorporated herein by reference or as disclosed inU.S. patent application Ser. No. 09/610,026 incorporated herein byreference.

[0051] To increase the mechanical strength of bone strips fabricatedfrom bone particles chemical linkages can be formed between adjacentbone particles. Such chemical linkages are obtained by partial orsuperficial demineralization of the bone to expose collagen on adjacentbone particles and forming collagen-collagen bonds, as described, e.g.,in U.S. patent application Ser. No. 09/020,205, incorporated herein byreference.

[0052] These chemical linkages can be formed employing a variety ofknown methods including chemical reaction, the application of energysuch as radiant energy, which includes irradiation by UV light ormicrowave energy, drying and/or heating and dye-mediatedphoto-oxidation; dehydrothermal treatment in which water is slowlyremoved while the bone tissue is subjected to a vacuum; and, enzymatictreatment to form chemical linkages at any collagen-collagen interface.The preferred method of forming chemical linkages is by chemicalreaction.

[0053] Chemical crosslinking agents include those that containbifunctional or multifunctional reactive groups, and which react withfunctional groups on amino acids such as epsilon-amine functional groupof lysine or hydroxy-lysine, or the carboxyl functional groups ofaspartic and glutamic acids. By reacting with multiple functional groupson the same or different collagen molecules, the reacting chemicalcrosslinking agent forms a reinforcing cross-bridge.

[0054] Suitable chemical crosslinking agents include: mono- anddialdehydes, including glutaraldehyde and formaldehyde; polyepoxycompounds such as glycerol polyglycidal ethers, polyethylene glycoldiglycidal ethers and other polyepoxy and diepoxy glycidal ethers;tanning agents including polyvalent metallic oxides such as titaniumdioxide, chromium dioxide, aluminum dioxide, zirconium salt, as well asorganic tannins and other phenolic oxides derived from plants; chemicalsfor esterification of carboxyl groups followed by reaction withhydrazide to form activated acyl azide functionalities in the collagen;dicyclohexyl carbodiimide and its derivatives as well as otherheterobifunctional crosslinking agents; hexamethylene diisocyanate;sugars, including glucose, will also cross-link collagen.

[0055] Glutaraldehyde cross linked biomaterials have a tendency toover-calcify in the body. In this situation, should it be deemednecessary, calcification-controlling agents can be used with aldehydecrosslinking agents. These calcification-controlling agents include:dimethyl sulfoxide (DMSO), surfactants, diphosphonates, amino oleicacid, and metallic ions, for example ions of iron and aluminum. Theconcentrations of these calcification-controlling agents can bedetermined by routine experimentation by those skilled in the art.

[0056] Chemical crosslinking involves exposing the bone particlespresenting surface-exposed collagen to the chemical crosslinking agent,either by placing the elements in a solution of the chemicalcrosslinking agent, or by exposing them to the vapors of the chemicalcrosslinking agent under conditions appropriate for the particular typeof crosslinking reaction. Such conditions include: an appropriate pH andtemperature, and for times ranging from minutes to days, depending uponthe level of crosslinking desired, and the activity of the chemicalcrosslinking agent. The bone particles are then washed to remove allleachable traces of the chemical.

[0057] When enzymatic treatment is employed, useful enzymes includethose known in the art which are capable of catalyzing crosslinkingreactions on proteins or peptides, preferably collagen molecules, e.g.,transglutaminase as described in Jurgensen et al., The Journal of Boneand Joint Surgery, 79-A (2), 185-193 (1997), herein incorporated byreference.

[0058] Formation of chemical linkages can also be accomplished by theapplication of energy. One way to form chemical linkages by applicationof energy is to use methods known to form highly reactive oxygen ionsgenerated from atmospheric gas, which in turn, promote oxygen cross-linkage between surface-exposed collagen. Such methods include using energyin the form of ultraviolet light, microwave energy and the like. Anothermethod utilizing the application of energy is a process known asdye-mediated photo-oxidation in which a chemical dye under the action ofvisible light is used to cross-link surface-exposed collagen.

[0059] Another method for the formation of chemical linkages is bydehydrothermal treatment which uses combined heat and the slow removalof water, preferably under vacuum, to achieve crosslinking of thebone-derived elements. The process involves chemically combining ahydroxy group from a functional group of one collagen molecule and ahydrogen ion from a functional group of another collagen moleculereacting to form water which is then removed resulting in the formationof a bond between the collagen molecules.

[0060] While cross-linking will improve the strength of the material, itmay reduce the osteoinductivity of the material. Therefore, whendesirable, a suitable inductive agent, e.g., BMP, DBM, etc., can beemployed to improve the osteoinductive properties of the tanned orcross-linked materials.

[0061] The mechanical strength of bone strips composed of the elongatedbone particles can also be increased by braiding the bone strips asdescribed above.

[0062] Medically/surgically useful substances which promote oraccelerate new bone growth or bone healing can be incorporated in, orassociated with, the mineralized or demineralized elongated bonesection(s). Useful substances of this kind which can be incorporatedinto the bone section(s) include, e.g., collagen, insoluble collagenderivatives, etc., and soluble solids and/or liquids dissolved therein,e.g., antiviral agents, particularly those effective against HIV andhepatitis; antimicrobials and/or antibiotics such as erythromycin,bacitracin, neomycin, penicillin, polymyxin B, tetracyclines, viomycin,chloromycetin and streptomycins, cefazolin, ampicillin, azactam,tobramycin, clindamycin, and gentamicin, etc.; biocidal/biostatic sugarssuch as dextran, glucose, etc.; amino acids; peptides; vitamins;inorganic elements; co-factors for protein synthesis; hormones;endocrine tissue or tissue fragments, synthesizers; enzymes such ascollagenase, peptidases, oxidases, etc.; polymer cell scaffolds withparenchymal cells; angiogenic drugs and polymeric carriers containingsuch drugs; collagen lattices; antigenic agents; cytoskeletal agents;cartilage fragments, living cells such as chondrocytes, bone marrowcells, mesenchymal stem cells; natural extracts; genetically engineeredliving cells or otherwise modified living cells; tissue transplants;demineralized bone powder (or “demineralized bone matrix” as it may alsobe referred to); DNA delivered by plasmid or viral vectors; autogenoustissues such as blood, serum, soft tissue, bone marrow, etc.;bioadhesives; bone morphogenic proteins; osteoinductive factor;fibronectin; transforming growth factor-beta; endothelial cell growthfactor; cementum attachment extracts; ketaserin; insulin-like growthfactors (IGF-1)(IGF-2); platelet derived growth factors (PDGF);epidermal growth factor (EGF); interleukin; human alphathrombin;fibroblast growth factors; periodontal ligament chemotactic factor;hormones, human growth hormone; animal growth hormone; growth hormonessuch as somatotropin; bone digesters; antitumor agents;immuno-suppressants; permeation enhancers, e.g., fatty acid ester suchas laureate, myristate and stearate monoesters of polyethylene glycol,enamine derivatives, alpha-keto aldehydes, etc.; and, nucleic acids.Preferred biomedically/surgically useful substances are bone morphogenicproteins and DNA delivered by plasmid or viral vector. Suitable methodsof incorporation include coating, immersion saturation, packing,co-lyophilization wherein the substance is placed on the bone graft andlyophilized, spraying, injecting into the bone tissue, etc. The amountsof medically/surgically useful substances utilized can vary widely withoptimum levels being readily determined in a specific case by routineexperimentation.

[0063] The biocompatible osteogenic band can also be fabricated in wholeor in part from tendon tissue. Tendon tissue itself is not osteogenic,but it can be made osteogenic by incorporating in, or associating with,the tendon tissue various osteogenic components as described above.Tendon tissue useful for fabricating the tension band includes, but isnot limited to, fascia lata, semitendinosus, achilles tendon and patellatendon tissue. The tendon tissue may be obtained from an autogeneic,allogeneic or a xenogeneic source, and preferably is obtained from anautogeneic or allogeneic source. The tendon can be excised and utilizedin its entirety or alternatively, is cut into at least one elongatedsection or a plurality of elongated sections by methods well known tothose skilled in the art. Reduction of the antigenicity of allogeneicand xenogeneic tendon tissue can be achieved by treating the tissue withvarious chemical agents, e.g., extraction agents such as monoglycerides,diglycerides, triglycerides, dimethyl formamide, etc., as described,e.g., in U.S. Pat. No. 5,507,810, incorporated herein by reference.Medically/surgically useful substances as described above can also beincorporated in or associated with the tendon tissue as described abovewith respect to tension bands fabricated from bone.

[0064] The biocompatible osteogenic band can also be fabricated in wholeor in part from ligament tissue. Ligament tissue itself is notosteogenic, but can be made osteogenic by the incorporation of variousosteogenic components as described above. Ligament tissue which isuseful in fabricating the tension band can comprise an entire excisedligament, or at least one elongated section of ligament or a pluralityof elongated sections of ligament. Ligament tissue can be obtained froman autogeneic, allogeneic or xenogeneic source, and preferably isobtained from an autogeneic or allogeneic source. The whole ligament canbe excised from the source by techniques well known in the art andutilized in its entirety or cut longitudinally into an elongated sectionor sections of ligament using conventional techniques known in the art.The whole ligament or section(s) of ligament can be further cut to thedesired size to conform to the region of the posterior spine beingrepaired. Ligament tissue obtained from an allogeneic or xenogeneicsource can be further treated by various agents to reduce itsantigenicity or with various medically/surgically useful substances asdescribed above.

[0065] When utilizing a plurality of ligament sections, such sectionscan be arranged to form a variety of structures as described above forelongated bone sections. For example, ligament sections can be twistedto form a bundle which can be then be utilized to form a braid of threeor more bundles. A plurality of ligament sections can be alignedlongitudinally to form an untwisted bundle, or two or more bundles ofligament sections can be wrapped about each other to form a helix.Preferably, the plurality of ligaments is woven into a braid.

[0066] The biocompatible osteogenic band can also be fabricated fromcollagen tissue which can be obtained from any autogeneic, allogeneic,or xenogeneic source, and preferably from an autogeneic or allogeneicsource. Collageneous tissue sources can include, but are not limited to,skin, tendon, intestine and dura mater, obtained from animals,transgenic animals, and humans. Collageneous tissue can also be obtainedby genetically engineering microorganisms to express collagen asdescribed, e.g., in aforementioned U.S. Pat. No. 5,243,038. Proceduresfor obtaining and purifying collagen are well known in the art andtypically involve acid or enzyme extraction as described, e.g., in U.S.Pat. No. 5,263,984, incorporated herein by reference. Collagen is alsocommercially available (Pentapharm Ltd., Basel, Switzerland). Thepurified collagen is then subjected to further processing to obtaincollagen fibers or collagen threads, which can optionally be treatedwith cross-linking agents, e.g., glutaraldehyde, to improve the fiber'sor thread's strength and/or various medically/surgically usefulsubstances as described above. The collagen threads can be arranged toform various structures, such as a woven or non-woven fabric, bundle orbraid, etc. by various techniques known in the art as described, e.g.,in U.S. Pat. Nos. 5,171,273 and 5,378,469, each incorporated herein byreference.

[0067] For example, U.S. Pat. No. 5,171,273 describes the preparation ofhigh-strength collagen fibers by dissolving Type I collagen in dilutehydrochloric acid, extruding the solution into a specific fiberformation buffer to reconstitute the collagen fibers. The reconstitutedcollagen fibers are subsequently cross-linked with glutaraldehyde orother chemical agents and treatments. The fibers are then processed intowoven or non-woven materials.

[0068] U.S. Pat. No. 5,378,469 describes methods for the production ofhigh strength collagen threads wherein collagen is extruded into adehydrating agent, e.g., polyethylene glycol, which has a higher osmoticpressure than that of the collagen solution and a pH from about 5 to 10which results in the formation of collagen threads. If desired, thecollagen threads can be cross-linked using various chemical agents. Thecollagen threads are then utilized to form braided constructs, pliedinto yarn, and knitted.

[0069] Various constructs of the collagen fibers and threads can beformed utilizing well known techniques, e.g., braiding, plying,knitting, weaving, that are applied to processing natural fibers, e.g.,cotton, silk, etc., and synthetic fibers made from syntheticbioabsorbable polymers, e.g., poly(glycolide) and poly(lactic acid),nylon, cellulose acetate, etc. See, e.g., Mohamed, American Scientist,78: 530-541 (1990).

[0070] For example, aforementioned U.S. Pat. No. 5,378,469 describes thebraiding of cross linked and non-cross linked collagen threads using aharness braiding machine (New England Butt Co., Providence, R.I.).Specifically, collagen thread is wound onto cylindrical stainless steelspools. The spools are then mounted onto the braiding carousel, and thecollagen thread is then assembled in accordance with the instructionsprovided with the braiding machine. In one particular run, a braid wasformed of four collagen threads, which consisted of two threads ofuncrosslinked collagen and two threads of cross linked collagen.

[0071] The collagen threads may also be plied into yarns using the samemethods and same machinery known to those skilled in the art in plyingthreads made out of other material, e.g., cotton, polyester, etc. Forexample, aforementioned U.S. Pat. No. 5,378,469 describes the productionof a 60 ply yarn from non-cross linked collagen threads. Therein, 4collagen threads were twisted together. Three of the resultant 4-plystrands were then twisted together in the opposite direction, and then 5of the resultant 12 ply strands were twisted in the opposite direction.

[0072] The collagen threads and/or braided collagen threads or pliedyarns can then be knitted into tubular or flat fabrics by usingtechniques known to those skilled in the art of producing fabricsmanufactured from other types of threads. Various medically/surgicallyuseful substances as described above can be incorporated in, orassociated with, the braided, knitted, or woven collagen.

[0073] The biocompatible osteogenic band can also be fabricated in wholeor in part from the submucosa of the intestine. Small intestinesubmucosa tissue is not osteogenic, but it can be made osteogenic byincorporating in, or associating with, the tendon tissue variousosteogenic components as described above. Preparation of small intestinesubmucosa from a segment of small intestine is described, e.g., in U.S.Pat. No., 4,902,508, incorporated herein by reference. The segment ofintestine which is obtained from an autogenic, allogeneic or xenogeneicsource, is subjected to mild abrasion to remove the outer layers (thetunica serosa and the tunica muscularis) and the inner layers. The smallintestine submucosa segment can be utilized in its entirety oralternatively, is cut into at least one elongated section or a pluralityof elongated sections by methods well known to those skilled in the art.The small intestine submucosa is then rinsed with saline and stored in ahydrated or dehydrated state.

[0074] The biocompatible osteogenic band can also be fabricated in wholeor in part from a synthetic biocompatible polymer or copolymer. As usedherein, “bioabsorbable polymer” refers to a polymer or copolymer whichis absorbed by the body. “Non-bioabsorbable polymer” refers to a polymeror copolymer which remain in the body without substantial bioerosion. Asused herein, “biocompatible” with respect to bioabsorbable andnon-bioabsorbable polymers means that the polymer does not elicitsubstantially adverse affects when implanted in living tissue. Examplesof synthetic biocompatible bioabsorbable polymers or copolymers include,but are not limited to, poly(lactide), poly(glycolide),poly(epsilon-caprolactone), poly(p-dioxanone),poly(epsilon-caprolactone-co-p-dioxanone) and poly(lactide-co-glycolide)as described, e.g, in U.S. Pat. Nos. 5,705,181 and 5,393,594, eachincorporated herein by reference; bioabsorbable block copolymers made ofhard phase forming monomers, e.g., glycolide and lactide, and soft phasemonomers, e.g., 1,4 dioxane-2-one and caprolactone, as described, e.g.,in U.S. Pat. No. 5,522,841, incorporated herein by reference. Otherbioabsorbable materials would include, e.g., natural materials such ascotton, and catgut. Examples of synthetic biocompatiblenon-bioabsorbable polymers include, but are not limited to, homopolymersand copolymers of polypropylene, polyamides, polyvinylchlorides,polysulfones, polyurethanes, polytetrafluoroethylene, etc. Biocompatiblepolymers are not osteogenic, but they can be made osteogenic byincorporating in, or associating with, the biocompatible polymersosteogenic components as described above. The biocompatible osteogenicband fabricated from the biocompatible polymer can have incorporatedwithin, or be associated with, medically/surgically useful substances asdescribed above.

[0075] In a particularly useful embodiment, the aforementionedosteogenic material making up the biocompatible osteogenic band can bewrapped with a monolithic piece, e.g., strips or sheets fabricated froma suitable material that is remodeled by the body and replaced over timewith new bone tissue. For example, the osteogenic material can bewrapped or surrounded with demineralized bone strips cut from sheetswhich are composed of elongated bone particles, commercially known asGRAFTON® Flex (Osteotech, Eatontown, N.J.) as described, e.g., inaforementioned U.S. Pat. No. 5,507,813 and U.S. application Ser. No.09/610,026.

[0076] These demineralized bone strips can be affixed to thebiocompatible osteogenic band by any convenient method, e.g., adheringthe strips to the biocompatible osteogenic band utilizing adhesives,suturing the strips to the biocompatible osteogenic band, braiding thestrips around the biocompatible osteogenic band, etc.

[0077] The biocompatible osteogenic band described herein can be affixedto at least one site on each of two or more vertebrae at any region ofthe anterior or posterior spine in need of repair, preferably theposterior spine, and more preferably the lumbar region which bearsheavier loads than other regions of the posterior spine. The site ofaffixation on each vertebra includes, but is not limited to, a vertebralbody, pedicle, transverse process, mamillary process, inferior articularprocess, superior articular process, spinous process and accessoryprocess. Preferably the site of affixation is the pedicle. FIG. 4 is adiagrammatic right lateral view of the described biocompatibleosteogenic band 7 affixed to the transverse processes of lumbarvertebrae.

[0078] Selection of the particular two or more vertebrae for affixationof the biocompatible osteogenic band will depend on the particularregion of the spine to be repaired and the nature of the spinaldisorder. The two or more vertebrae can include adjacent vertebrae,alternating vertebrae, or a combination thereof. For example, thebiocompatible osteogenic band can be affixed to adjacent lumbarvertebrae L4 and L5; alternating lumbar vertebrae L1, L3 and L5; andadjacent and alternating lumbar vertebrae L1, L2 and L4.

[0079] Preferably, the biocompatible osteogenic band is affixed to twoor more vertebrae on each side of the posterior spine in a symmetricalmanner. For example, FIG. 5 shows a biocompatible osteogenic band 7affixed to each side of the posterior spine on the third and fourthlumbar vertebrae. The biocompatible osteogenic band can be affixed tothe vertebrae using any known surgical method, e.g., using bone screws,cement, hooks, friction, tying, pinning etc.

[0080] An example of a surgical procedure for affixing the describedbiocompatible osteogenic band to two vertebrae of the posterior spinecomprises drilling a hole in the pedicle of each of the two vertebrae,wherein each hole is adapted to fit a pedicle screw. A pedicle screwhaving a threaded end portion is then screwed into the hole in each ofthe two pedicles using a screw driver. A biocompatible osteogenic bandcontaining a hole fabricated at one of its ends is then affixed to thesuperior vertebra by inserting the threaded end portion of the pediclescrew fastened in the superior pedicle through the hole in thebiocompatible osteogenic band. A nut is then secured to the threaded endportion of the fastened pedicle screw to secure the biocompatibleosteogenic band to the superior vertebra. To load the linkage, i.e., tomaintain the two or more vertebrae under tension, the posteriorvertebrae between the two pedicle screws are then compressed. The degreeto which the posterior vertebrae between the pedicle screws should becompressed will vary depending on the nature of the spinal disorder, thesite of attachment of the ends of the biocompatible osteogenic band, thedistance between the two vertebrae, and the amount of tension whichneeds to be placed on the posterior spine and can be determined by thesurgeon during the surgical procedure. The other end of thebiocompatible osteogenic band having a hole fabricated therein is thenaffixed to the posterior vertebra by inserting the threaded end portionof the pedicle screw fastened in the posterior vertebra through the holeat the other end of the tension band. A nut is then secured to thethreaded end portion of the fastened pedicle screw in the posteriorvertebra to secure the other end of the biocompatible osteogenic band tothe posterior vertebra.

[0081] In a particularly useful embodiment, the present method isutilized in conjunction with other known methods for repairing thespine, particularly intervertebral spinal fusion, which is oftenperformed to treat an anomaly involving an intervertebral disc caused byinjury, disease or a degenerative disorder. Intervertebral spinal fusionis typically carried out by completely removing the intervertebral discand inserting an anterior supporting structure 8, inside the interbody,interdiscal space to facilitate repair and healing (see FIG. 6). Overtime, bone grows across the anterior supporting structure and theadjacent vertebrae grow together and fuse.

[0082] Various types of anterior supporting structures have beenemployed in intervertebral spinal fusion and are well known in the artsuch as a plug, bone dowel, prosthesis, cage device, bone graft, e.g., amachined allograft or autograft bone substitute, femoral ring, iliaccrest graft, fibula, etc. For example, U.S. Pat. Nos. 4,834,757 and4,878,915, each incorporated herein by reference, describe the use ofplugs which are inserted into the disc space. In U.S. Pat. No.,4,834,757 the plug is a biocompatible composite cage which is intendedto contain autologous or allogeneic bone to facilitate and promote boneingrowth. In U.S. Pat. No. 4,878,915 the plug is a solid devicecontaining barbs for biting into the bone as well as spaces between thebarbs to facilitate bone ingrowth. U.S. Pat. No. 5,895,428, incorporatedherein by reference, describes an implant having an upper member whichpivots and is locked to a lower member. The upper portion of the uppermember and the lower portion of the lower member engage adjacentvertebra and have ceramic surfaces which allow bone ingrowth. U.S. Pat.No. 5,899,939, incorporated herein by reference, describes adowel-shaped bone-derived implant. U.S. Pat. No. 6,045,580, incorporatedherein by reference, describes a bone implant derived from the iliaccrest. U.S. Pat. No. 5,972,368, incorporated herein by reference,describes the use of bone graft substitute compositions and spacerswhich include a body composed of a deactivated bone graft. The body ofthe spacer can include flat spacers, bone dowels, cortical rings, bonechips and other suitably shaped bone pieces. Bone dowels from allogeneicfemoral or tibial condyles are also commercially available fromOsteotech, Inc. Medically/surgically useful substances and osteogeniccomponents as described above with respect to the tension band can alsobe incorporated in, or associated with, the anterior supportingstructure.

[0083]FIG. 6 depicts a biocompatible osteogenic band 7 used inconjunction with an anterior supporting structure 8 to repair a spinaldisorder. The anterior supporting structure 8 is inserted in the discspace between adjacent vertebrae prior to affixing the biocompatibleosteogenic band 7 to the adjacent vertebrae of the posterior spine. Forexample, after the anterior supporting structure 8 is inserted in thedisc space between the adjacent vertebrae, the biocompatible osteogenicband 7 can be affixed to the posterior spine by rocking the vertebraback using the anterior supporting structure 8 as a fulcrum and affixingthe biocompatible osteogenic band 7 to the posterior spine.

[0084] In a particularly useful embodiment, a method of repairing aspinal disorder is provided which comprises inserting an anteriorsupporting structure in the disc space between adjacent vertebrae of aspine and then affixing a biocompatible osteogenic band fabricated ofbone to two or more vertebrae of the spine, preferably the posteriorside of the spine, to maintain the two or more vertebrae under tension.Preferably the biocompatible osteogenic band fabricated of bonecomprises at least one elongated section of bone or a plurality ofelongated sections of bone, and more preferably the bone section orsections are segmentally demineralized. In a most preferred embodiment,the segmentally demineralized bone sections are braided. In aparticularly useful embodiment, the anterior supporting structure is abone dowel.

[0085] While the present method of repairing a spinal disorder is usefulin humans, it is also useful in treating many different types ofanimals, e.g., dogs, horses and the like.

[0086] The following example is meant to illustrate but not limit theinvention.

EXAMPLE Band Tensile Tests

[0087] Specimens were prepared from diaphyseal human cortical bone byfirst making transverse cuts to prepare a diaphyseal segment of theappropriate length, followed by longitudinal cuts. In this way, foursegments were made having length 6 mm; and four segments were madehaving length 10 mm. The width and thickness of each test article wasmeasured using a Mitutoyo Model 500-196CE digital caliper. Thicknesseswere measured at three sites each and averaged (Table). Widths of thesegments were also measured at three locations and averaged (Table). Onespecimen of the 6 mm length and one specimen of the 10 mm length wereeach covered on their ends by an elastic (synthetic rubber) balloon,fitted tightly around the piece. Other specimens were not masked in thisway. All specimens were demineralized using 15 mL of 0.6N HCl acid pergram of weight, for 3 days, when all unmasked regions were welldemineralized and flexible.

[0088] A uniaxial servo-hydraulic test machine (MTS model 858 Bionix)was used under displacement control to apply a constant tensiledisplacement to the test articles at a rate of 5 mm/min. The testarticle holding fixtures consisted of two vise-like grips, which werehand-tightened to attach each test specimen to the load cell (lowergrip) and the actuator (upper grip). Tests terminated at failure of thetest article. A 100 kN load cell was used to record load levels for alltests. As shown in the table below, average ultimate load and ultimatestrength were 0.47 kN and 12.99 MPa respectively for the 6 cm longspecimens, and 0.32 kN and 8.65 MPa respectively for the 10 cm longspecimens. TABLE Average Average Ultimate Ultimate Width 1 Width 2 Width3 Thickness 1 Thickness 2 Thickness 3 Width Thickness Area Load Stressmm mm. mm. mm. mm. mm mm mm mm² kN MPa  6 cm-1 10.93 10.61 10.35 2.632.91 2.94 10.63 2.83 30.05 0.35 11.68 (undemineralized ends)  6 cm-212.09 12.42 12.87 3.24 3.07 2.78 12.46 3.03 37.75 0.65 17.22  6 cm-312.07 12.36 12.21 2.80 2.35 3.11 12.21 2.75 33.63 0.49 14.45  6 cm-412.02 12.08 12.17 4.00 3.73 3.99 12.09 3.91 47.23 0.41 8.62  6 cmaverage 11.78 11.86 11.9 3.17 3.02 3.21 11.85 3.13 37.17 0.47 12.99 10cm-1 11.16 11.61 10.70 3.01 3.16 2.93 11.16 3.03 33.84 0.35 10.37(undemineralized ends) 10 cm-2 11.22 11.33 10.47 4.04 4.21 3.85 11.014.03 44.39 0.31 6.67 10 cm-3 10.36 9.77 9.42 4.22 3.70 3.43 9.85 3.7837.27 0.30 8.08 10 cm-4 11.43 10.69 10.84 3.21 3.15 3.17 10.99 3.1834.90 0.32 9.28 10 cm average 11.04 10.85 10.36 3.62 3.56 3.35 10.753.51 37.6 0.32 8.6

[0089] It will be understood that various modifications may be made tothe embodiments disclosed herein. Therefore, the above descriptionshould not be construed as limiting, but merely as exemplifications ofpreferred embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

1. A method for repairing a joint formed by at least two adjacentvertebrae the method comprising: providing a biocompatible osteogenicband comprising bone having a first end and a second end, and affixingsaid first end of the biocompatible osteogenic band to a first vertebraand affixing said second end to a second vertebra, the first and secondvertebrae being identical to, or encompassing, the adjacent vertebrae,to maintain the joint formed by the adjacent vertebrae under tension. 2.The method of claim 1 further comprising affixing said osteogenic bandto at least one other vertebrae.
 3. (Canceled)
 4. The method of claim 1wherein the osteogenic band comprises cortical bone.
 5. The method ofclaim 1 wherein the osteogenic band comprises bone selected from thegroup consisting of autogenetic bone, allogeneic bone and xenogeneicbone.
 6. The method of claim 1 wherein the osteogenic band comprises atleast one elongated section of bone.
 7. The method of claim 6 whereinthe elongated section of bone is demineralized.
 8. (Canceled)
 9. Themethod of claim 7 wherein the elongated section of bone is segmentallydemineralized.
 10. The method of claim 6 wherein the bone comprises aplurality of elongated sections of bone.
 11. The method of claim 10wherein the plurality of elongated sections of bone is demineralized.12-17. (Canceled)
 18. The method of claim 1 wherein the osteogenic bandcomprises demineralized bone.
 19. The method of claim 18 wherein thedemineralized bone is in a form selected from the group consisting of apowder, particles, gel, liquid and monolithic piece.
 20. The method ofclaim 19 wherein the demineralized bone is in the form of a monolithicpiece.
 21. The method of claim 1 wherein the biocompatible osteogenicband further comprises one or more substances selected from the groupconsisting of an antiviral agent, antimicrobial agent, antibiotic agent,biocidal/biostatic sugar, amino acid, peptide, vitamin, inorganicelement, protein synthesis cofactor, hormone, endocrine tissue,synthesizer, enzyme, polymer-cell scaffold with parenchymal cells,angiogenic drug, collagen lattice, antigenic agent, cytoskeletal agent,cartilage fragment, chondrocytes, bone marrow cells, mesenchymal stemcells, natural extract, genetically engineered living cells, tissuetransplant, demineralized bone powder, DNA, bioadhesive, bonemorphogenic protein, osteoinductive factor, fibronectin, transforminggrowth factor-beta, endothelial cell growth factor, cementum attachmentextracts, ketaserin, insulin-like growth factor, platelet derived growthfactor, epidermal growth factor, interleukin, human alphathrombin,fibroblast growth factor, periodontal ligament chemotactic factor,growth hormone, bone digester, antitumor agent, immuno-suppressant,permeation enhancer and nucleic acid.
 22. The method of claim 1 whereinthe biocompatible osteogenic band is affixed to the posterior side of aspine.
 23. The method of claim 22 wherein the site of affixation of theosteogenic biocompatible band to the two or more vertebrae of the spineis selected from the group consisting of vertebral body, pedicle,transverse process, mamillary process, inferior articular process,superior articular process, spinous process and accessory process.24-39. (Canceled)
 40. The method of claim 1 wherein the biocompatibleosteogenic band has a dimension between about 1 cm and about 1 meter inlength, between 2 mm and about 30 mm in thickness, and between about 2mm and about 30 mm in width.
 41. The method of claim 1 wherein both endsof the biocompatible osteogenic band are affixed to posterior sites onthe vertebrae.
 42. The method of claim 1 wherein said first end of saidbiocompatible osteogenic band is affixed to the pedicle, transverseprocess, mamillary process, inferior articular process, superiorprocess, spinous process or accessory process of the first vertebrae andsaid second end of said biocompatible osteogenic band is affixed to thepedicle, transverse process, mamillary process, superior articularprocess sinous process or accessary process of the second vertebrae.